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                [Poi2000]滑雪                </h1>
                <p>时间限制：1s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：128MB</p>			</div>
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                                <h3>题目描述</h3><p><div align="center"></div>
<div style="text-indent: 21pt"><span style="font-size: medium">一个滑雪队在Byte山上组织了一次训练。山的北坡有一个滑雪场，所有的滑雪者都要从山上的起点站滑到山下的终点站。此次训练中各队员同时出发到终点站会合，除了始末两处外，队员们的滑雪路径不能相交，且山上的滑雪道只能从上往下滑。</span></div>
<div style="text-indent: 21pt"><span style="font-size: medium">滑雪道的分布地图由多块被林地连接的空地组成，每块空地都处于不同的高度。两块空地间至多由一块林地连接。滑雪过程中，滑雪者可以选择路径访问任一空地（但不必全部经过）。各滑雪道只在空地相会，既不穿隧道，也不临空飞越。</span></div>
<div><span style="font-size: medium"><b>任务：</b></span></div>
<div style="text-indent: 18pt"><span style="font-size: medium">编写一个程序完成下列工作：</span></div>
<div style="margin: 0cm 0cm 0pt 36pt; text-indent: -18pt"><span style="font-size: medium">●<span style="font: 7pt 'Times New Roman'">&nbsp;&nbsp; </span>读入滑雪场的地图；</span></div>
<div style="margin: 0cm 0cm 0pt 36pt; text-indent: -18pt"><span style="font-size: medium">●<span style="font: 7pt 'Times New Roman'">&nbsp;&nbsp;&nbsp;&nbsp; </span>算出能参加训练的最大队员数；</span></div>
<div style="margin: 0cm 0cm 0pt 36pt; text-indent: -18pt"><span style="font-size: medium">●<span style="font: 7pt 'Times New Roman'">&nbsp;&nbsp;&nbsp;&nbsp; </span>把结果输出</span></div></p><hr/><h3>输入格式</h3><p><div>&nbsp;<span style="font-size: medium">第一行是空地的数目n，2&le;n&le;5000。以下n-1行，每行都有一些用空格分开的整数，第(i+1)行的数字描述的是从空地i沿林地往下可到达的其它空地。该行第一个整数k表示这些空地的个数，以下k个整数即它们的编号，按从东到西的顺序排列(即通向各空地的林地的位置)。空地从1到n编号。起点站建于空地1，终点站建于空地n。</span></div></p><hr/><h3>输出格式</h3><p><div><span style="font-size: medium">&nbsp;&nbsp;仅一行，包括一个整数，即能参加训练的最大人数。</span></div></p><hr/><h3>样例输入</h3><pre>15
5 3 5 9 2 4
1 9
2 7 5 
2 6 8
1 7
1 10
2 14 11
2 10 12
2 13 10
3 13 15 12
2 14 15
1 15
1 15
1 15
</pre><hr/><h3>样例输出</h3><pre>3</pre><hr/><h3>提示</h3><p>没有写明提示</p><hr/><h3>题目来源</h3><p>没有写明来源</p>
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